#include<stdio.h>
#include<math.h>
int main()
{
    double x1, y1, x2, y2, x3, y3;
    scanf("%lf %lf", &x1, &y1);
    scanf("%lf %lf", &x2, &y2);
    scanf("%lf %lf", &x3, &y3);
    double s1 = sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
    double s2 = sqrt((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1));
    double s3 = sqrt((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3));
    printf("%.2f", s1 + s2 + s3);
    return 0;
}